This invention is directed to improved antitussive swallowable liquid compositions for oral use. Oral cough preparations, such as syrups, solutions, suspensions and the like, containing an effective antitussive agent have long been used for the symptomatic relief of coughs. The most popular of such preparations contain either dextromethorphan or its hydrobromide salt or codeine or its sulfate salt as the active antitussive agent.
Phenol is a known topical anesthetic, which has been used to treat minor sore mouth and sore throat pain. The mode of action, fast acting but not long lasting, is that it desensitizes sensory nerve receptors present in the mucous membranes of the throat and oral cavity to exert its local anesthetic effect. Previous dosage forms of administration have included aqueous solutions of 1.4% phenol for use as a mouthwash, rinse or gargle, which is expelled from the oral cavity after use, and as a throat spray. Such forms provide topical application of an effective dose of phenol directly to the mucous membranes or mouth tissues. The ensuing anesthesia/analgesia lasts so long as an effective concentration of the phenol is supplied to the site of action. As the phenol is washed away, e.g., by saliva, the anesthetic/analgesia action recedes.
Solid lozenge forms of the antitussive agent, dextromethorphan hydrobromide (10 mg), and phenol (32.5 mg) are known to be commercially available in Canada for the respective systemic treatment of coughs and local treatment of accompanying irritated throat. Also in British Patent No. 1,144,915, medicinal two-phase solid pastille forms containing (among others) dextromethorphan and phenol in the separate phases are disclosed for the respective treatment of cough and sore throat relief. Such solid lozenge and pastille forms require the action of saliva over an extended period of time for dissolution of the solid form, thereby effectuating release of the respective active ingredients and prolonged contact of phenol at the mucosal membrane throat site.
To date, however, applicants herein are unaware of any combination of an effective oral antitussive drug and phenol in a liquid composition for administration by immediate swallowing.
It has now been found that the combined use of phenol and an oral antitussive drug in a swallowable liquid provides improved relief to an individual afflicted with cough or cough and associated sore throat, without the aforementioned need for prolonged contact with mucosal membranes of the throat and oral cavity.